The provision of electrical lead-throughs from atmospheric environments into a vacuum system has associated with it numerous difficulties, such as: the formation of a high quality seal; the requirement for very low out gassing from the materials used in the lead-through structure; and the need to have a lead-through structure which can withstand the forces resulting from the high differential pressure between a high vacuum environment and an atmospheric environment, or equally between a high vacuum and an ultra-high vacuum region. The conventional way of attempting to overcome these problems has been to use feed-throughs comprising metallic pins or tracks extending through a body of ceramic material. Such technology has enabled the interfacing of a moderate amount of separate connections from atmospheric into vacuum environments. However, a disadvantage of this technique is that it provides a limited signal density (i.e. there is a limit to the minimum spacing of the conductive pins through the ceramic). This conventional technology has, typically, not been able to provide a lead through structure with more than 500 parallel connections.